Lactobacillus plantarum, the Cause of “Yeast Spots” on Olives

Abstract

One of the most common abnormalities associated with olives pickled in California is known throughout the industry as "yeast spots." This blemish, shown in figure 1, is characterized by the formation of raised white spots or pimples between the inner surface of the skin and the flesh of the olive. Although in general, the Sevillano variety most frequently shows this blemish, the spots may be found on all varieties and types of olives which have undergone fermentation in salt brines.' Because such olives are considered unsightly, some loss of value of the pickled fruit may be experienced, although the olives may be perfectly normal and healthful in other respects.These small white spots actually are colonies of microorganisms which have developed during the fermentation. Vaughn, Douglas and Gililland (1943) reported that most of the pimples examined in the laboratory contained lactobacilli, some cultures of which were identified as Lactobacillue plantarum. Then a deliberate search for yeasts was initiated because general use of the term "yeast spots" indicated that yeasts actually had been observed in the pimpled olives. No yeasts were found. After it was apparent that most, if not all, of the spots contained bacteria, it was decided to determine the predominating types. These investigations are described in the following pages. EXPERIMENTAL METHODS SamplesCalifornia olives collected for examination included Spanish type green olives, Sicilian type green olives, brined Greek type olives, storage fruit held in brines for subsequent preparation of ripe olives, and canned ripe olives. Authentic samples of Spanish green olives also were obtained.An individual sample consisted of at least 10 spotted olives. Between 1942 and 1952, 115 different samples were examined. These included 40 Spanish type, 25Sicilian type, 5 brined Greek type, 30 brined storage, 5 canned ripe and 10 authentic Spanish olive samples. Microscopic ExaminationTo determine whether bacteria or other microbes were present, the contents of at least 10 spots on each

Pustule Formation by Lactobacilli on Fermented Vegetables

“…This report extends the observations of Vaughn et al (1953), who investigated only white spots on olives, to fermented tomatoes and cucumbers. In contrast to the results of these workers who found only L. plantarum, wve have isolated two species responsible for producing pustules in tomatoes, L. plantarum and L. leichmannii.…”

Homofermentative Lactobacilli of Ciders including Lactobacillus mali nov. spec.

“…IN THE PREPARATION of any food that depends on an acid fermentation such as sauerkraut, olives or even ensiled grass, one of the organisms invariably present is Lactobacillus plantarum (Pederson, 1930;Vaughn et al, 1953;Keddie, 1959). In spite of its ubiquity in those substrates already mentioned, this species is much less frequently found in beers or wines and rarely in ciders.…”